This invention relates to support appliances and is in particular concerned with the construction of a mattress or bed in which a plurality of inflatable air sacs provide a support surface. In our British Patent Specification No. 1,474,018 there is described a bed of the above type which includes air operated bellows for raising and lowering the foot and/or head of the bed. The bed described in this British patent specification includes a sub-frame which is pivotably mounted on a carriage and includes means such as an electrically driven rack for altering the attitude of the sub-frame with respect to the carriage. The inflatable air sacs are mounted on support members which are pivotably connected to the sub-frame and bellows are provided for altering the angle of the support members with respect to the sub-frame.
While the bed described in our above mentioned patent specification has proved to be successful and effective in nursing seriously ill patients, there is a need for a support appliance which can be made more cheaply and can be fitted to a standard hospital bed frame.